This invention relates to a method of making a vehicle windshield. More particularly, this invention relates to a method of making a vehicle windshield in which an opaque layer on a substrate (e.g., glass sheet) of the windshield extends up to a peripheral edge thereof.
Opaque layers are known for use on automotive and/or architectural glass. Such opaque layers are used, for example, to form opaque borders around the peripheral marginal surfaces of glazings used as windshields, side lites and/or backlites of motor vehicles. These borders are used to obstruct from view attachment devices for the glazings, and/or to protect adhesives or other materials from exposure to light which could possibly degrade them.
Known opaque layers include both ceramic enamels and water-based paints. Either one, as well as any other suitable opaque layer, may be used in conjunction with the instant invention. For purposes of example only, and without limitation, any of the opaque layers discussed or utilized in any of U.S. Pat. Nos. 4,954,153, 4,959,090, 5,443,669, 5,518,535, 5,698,026, or 6,126,737, may be utilized in conjunction with the instant invention. Each of these patents are hereby incorporated herein by reference.
With regard to opaque layers of ceramic enamel(s), for example, such layers are often dark or black in color due to the presence of colorant oxides such as chrome oxide, cobalt oxide, and/or nickel oxide. Typically, the opaque enamel is applied to a glass substrate in a predetermined pattern in any convenient manner including but not limited to silk screening or screen printing. Thereafter, the enamel is xe2x80x9cfiredxe2x80x9d onto the glass, i.e., heated in order to melt (or at least partially melt) the enamel frit and fuse it to the glass surface. The firing temperature and length of time at such temperature required for firing (or curing) the opaque enamel depends on, among other things, the type and amount of frit as well as the thickness of the enamel. Thicker enamel layers with more glass frit therein, for example, require higher temperatures and/or longer exposures at the firing temperature in order to bond the enamel to the glass substrate. For example, firing of opaque enamel layers may require temperatures in excess of 540 degrees C, even over 590 degrees C in certain instances.
Water-based opaque layers are similar in color to the opaque enamel layers discussed above. However, when water-based opaque layers are used, they are painted onto or otherwise applied to the substrate (e.g., glass substrate) and in some instances may be cured by baking at a lesser temperature (e.g., from about 200-440 degrees C.).
FIG. 1 is a flow chart illustrating a conventional method for making a vehicle windshield. As will be appreciated by those skilled in the art, a vehicle windshield typically includes first and second glass substrates (same as sheets herein) laminated to one another via a polymer based interlayer. The substrates/sheets may be flat or bent in different embodiments of this invention. As shown in FIG. 1, the inner and outer glass sheets are first cut into the desired windshield shape (step 1). Thereafter, what is to be the inner glass sheet is painted (e.g., via a silk screening technique) with an opaque enamel layer (step 2). The enamel is then xe2x80x9cfiredxe2x80x9d into/onto the inner glass sheet, and the two glass sheets are thereafter heat bent in a conventional manner (step 3). After heat bending, the two sheets are laminated together via a polymer based interlayer, with the opaque layer being provided around the peripheral border of surface #4 (i. e., the surface of the inner sheet facing the vehicle interior) of the resulting windshield (step 4).
More particularly, reference is made to FIGS. 2-7 with regard to the aforesaid conventional technique of making vehicle windshields. As shown in FIG. 2a, the opaque layer material 9 is screen printed onto a border area of what is to be the inner glass substrate/sheet 11, after the sheet has been cut into its windshield shape. When silk screening is used to apply the opaque layer to the substrate, a silk screening drum 7 may be utilized in forming the enamel based opaque layer on the substrate 11. After the enamel has been heated and xe2x80x9cfiredxe2x80x9d, the resulting inner sheet is shown in FIG. 2b. In particular, as can be seen in FIG. 2b, the fired opaque enamel layer 9 is located around a peripheral area of the glass sheet 11, but is spaced inwardly from the peripheral edge thereof. If attempts were made to silk screen apply the opaque enamel layer up to the edge of the substrate, this would likely cause opaque enamel material to drip or run down the peripheral edge(s) of the substrate which would be undesirable. Accordingly, using conventional techniques, opaque layers 9 do not typically extend all the way up to the edge of a cut glass sheet upon which they are formed.
After (or before in certain instances) the opaque layer 9 has been fired onto the inner glass substrate/sheet 11, the inner glass substrate 11 is stacked onto or together with what is to be the outer glass substrate/sheet 13 of the windshield as shown in FIG. 3. Thereafter, the two flat substrates 11, 13 are heat bent utilizing a heat source 15, as shown in FIG. 4. A heat source 15 may be provided on one or both sides of the sheets in FIG. 4, although only one source is illustrated for purposes of simplicity. After heat bending, the two bent glass sheets/substrates 11, 13 are separated as shown in FIG. 5, and a polymer based interlayer 17 is placed therebetween as shown in FIG. 6. The bent glass sheets 11, 13 are then laminated to one another with polymer based interlayer 17 therebetween so as to form the resulting laminated windshield of FIG. 7.
FIG. 8 is a side cross-sectional view of the windshield of FIG. 7. In particular, the windshield includes inner glass sheet 11, outer glass sheet 13, polymer based interlayer (e.g., of polyvinyl butyral (PVB)), optional low-e coating 19, and opaque enamel layer 9 provided around the periphery of the #4 surface of the windshield. As previously mentioned, opaque enamel layer 9 does not extend all the way to the edge 11a of inner glass sheet 11. In particular, the opaque layer 9 is spaced inwardly from edge 11a by a distance xe2x80x9cDxe2x80x9d as shown in FIG. 8.
A growing trend in vehicles (e.g., cars, pick-up trucks, sport utility vehicles, minivans, etc.) is to utilize exposed edge windshields. However, with exposed edge windshields (or other vehicle windows), the spacing of opaque layer 9 inwardly a distance xe2x80x9cDxe2x80x9d from the peripheral edge 11a of the windshield is undesirable for aesthetic reasons. Instead, it is believed that it would be more aesthetically pleasing if the opaque layer could be formed so as to extend all the way up to the edge 11a of the windshield. Unfortunately, as explained above, this is not practical using conventional techniques, because for example if one attempts to silk screen opaque layer 9 onto an already cut glass sheet 11 all the way up to the edge 11a thereof, the opaque material will tend to drip or run down the edge 11a `thereby becoming aesthetically unattractive or requiring extensive clean-up procedures.
In view of the above, it will be appreciated by those skilled in the art that there exists a need for a method of manufacturing a vehicle windshield (or other window) whereby an opaque layer (e.g., enamel or water based) can be formed so as to extend all the way up to the peripheral edge of the glass sheet upon which it is located in the final product. There also exists a need in the art for the resulting windshield product.
An object of this invention is to provide a method of making a vehicle windshield or other window.
Another object of this invention is to provide a method of making a vehicle windshield whereby an opaque layer (e.g., enamel or water based) may be formed so as to extend all the way up to the peripheral edge of the resulting windshield. Such a feature is believed to be aesthetically pleasing, especially in exposed edge windshield applications.
Another object of this invention is to provide a method of making a vehicle windshield, wherein the opaque layer is applied to a glass substrate before the glass substrate is cut into its desired windshield shape. After application of the opaque layer and firing/curing of the same, the glass sheet is cut into the desired windshield shape along a cutting line which is aligned so that the cut is made through both the glass sheet and the opaque layer thereon so that the resulting sheet has the opaque layer extending all the way up to at least a portion of the edge thereof. Thereafter, the coated sheet may be laminated to another glass sheet in order to form the resulting windshield.
Another object of this invention is to xe2x80x9cfirexe2x80x9d or cure an applied opaque layer (enamel or water based) on a glass sheet using microwave energy.
Another object of this invention is to fulfill one or more of the above-listed objects.
Generally speaking, certain example embodiments of this invention fulfill one or more of the above-listed objects by providing a method of making a vehicle windshield, the method comprising:
providing a first glass sheet;
applying an opaque layer on the first glass sheet;
firing or curing the opaque layer on the first glass sheet using microwave energy;
after the firing or curing of the opaque layer on the first glass sheet, cutting the first glass sheet along a cutting line into a desired peripheral shape, wherein the cutting along the cutting line extends through both the first glass sheet and the fired or cured opaque layer thereon so that after said cutting the opaque layer extends all the way to a peripheral edge of the cut glass sheet; and
laminating the cut first glass sheet to a second glass sheet in order to form the vehicle windshield.
Certain other embodiments of this invention fulfill one or more of the above listed objects by providing a method of making a window, the method comprising:
providing a first glass sheet;
applying a dark colored or black opaque layer on the first glass sheet;
firing or curing the dark colored or black opaque layer on the first glass sheet;
after the firing or curing of the dark colored or black opaque layer on the first glass sheet, cutting the first glass sheet along a cutting line into a desired peripheral shape, wherein the cutting along the cutting line extends through both the first glass sheet and the fired or cured opaque layer thereon so that after said cutting the opaque layer extends all the way to a peripheral edge of the cut first glass sheet.